1. Field of the Invention
The present invention relates to a hard disk drive, and more particularly, to a servo burst signal recording method for recording a servo burst signal in an improved form, and a disk recording medium on which the servo burst signal is recorded by the servo burst signal recording method.
2. Description of the Related Art
An integrated head in which a thin-film inductive element for a recording mode combined with a magneto-resistive (MR) sensor for a reading mode has been developed in order to heighten a recording density and a recording/reproduction efficiency in a digital signal recording/reproducing apparatus such as a hard disk drive. The integrated bead includes a coil disposed between two poles and a MR sensor disposed between two shields.
An integrated recording head includes a recording element having an upper pole, a lower pole, a coil disposed between the upper and lower poles, and a reading element including an upper shield, a lower shield, and an MR sensor disposed between the upper and lower shields.
The recording element and reading element are disposed so that a predetermined distance is maintained between the coil and the MR sensor. The width W1 of the recording element is larger than the width W2 of the reading element. The reasons is because the width of the reading element does not need to be large since the sensitivity of the MR sensor is very high. The width W1 of the recording element, the width W2 of the reading element and the width of the track are defined as the diametric direction of the disk.
If an MR sensor is used, the reading characteristics of the head are not influenced by the frequency of the recording signal. However, since the width W2 of the reading element is smaller than the width W1 of the recording element, in a hard disk drive using the integrated head, a dead zone occurs during a servo operation. The dead zone is an area where the magnitude of a burst signal detected by a head does not vary within a certain range, although a track-off phenomenon occurs in which the head deviates from the center of a track.
It is important that the position of the head is controlled with respect to the center of the track on a disk, in order to ensure the accuracy of a recording/reading operation of the head in a disk drive. A sampled servo system is known as a disk drive servo system. In this system, a servo burst signal is recorded on each servo track on the disk. The servo burst signal is read by the head and is used for generating a position error signal representing a mismatch between the head and the center line of the track on the disk.
As is well-known, the servo burst signal is recorded by the recording element during a servo writing operation. The width W1 of the recording element is equal to that of the track. However, the width of the MR sensor is smaller than the width W1 of the recording element or the width W of the track in the integrated head. Thus, the occurrence of the dead zone cannot be avoided in the recording medium having the burst signal recorded thereon. As a result, the accuracy of a tracking control is lowered.
The following patents each discloses feature in common with the present invention: U.S. Pat. No. 5,796,543 to Ton-That, entitled Data Track Pattern Including Embedded Servo Sectors For Magneto-Resistive Read/Inductive Write Head Structure For A Disk Drive, U.S. Pat. No. 5,596,463 to Hashimoto, entitled Recording/Reproduction Apparatus With An Integrated Inductive Write, Magnetoresistive Read Head, U.S. Pat. No. 5,469,113 to Steyaert et al., entitled Rectifier And Integrator Circuit For Disk Drive Servo System, U.S. Pat. No. 5,483,393 to Mento et al., entitled Disk Drive Having Head Positioning Servo With Improved Servo Read Signal Processing Using Median Servo Burst Peak Magnitudes, U.S. Pat. No. 5,581,420 to Chainer et al., entitled Method And System For Determining A Radial Positioning Valve Used For Writing Tracks At A Desired Track Pitch, U.S. Pat. No. 5,576,910 to Romano et al., entitled Burst Comparison And Sequential Technique For Determining Servo Control In A Mass Storage Disk Device, U.S. Pat. No. 4,811,135 to Janz, entitled Tri-Phase Servo Pattern For Providing Information For Positioning The Transducers OF A Magnetic Disk Storage Drive, and U.S. Pat. No. 5,602,293 to Brunnett et al., entitled Method And Apparatus For Sensing Position In A Disk Drive.
To solve the above problems, it is an objective of the present invention to provide a servo burst signal recording method for more accurately a tracking control in a hard disk drive using a head having a reading element having a width smaller than that of a recording element.
It is another object of the present invention to provide a recording medium on which a servo burst signal is recorded by the above servo burst signal recording method.
To accomplish the above object of the present invention, there is provided a servo burst signal recording method for recording servo burst signals on at least two servo burst regions which are deviated in a diametrical direction in tracks of a disk recording medium, the servo burst regions each being divided into at least two sub-regions in the traveling direction of a head, one sub-region having the same width as that of a track, and the other sub-region having a smaller width than that of the track.
There is also provided a disk recording medium having at least two servo burst regions on which servo burst signals are recorded in a diametrical direction in tracks of the disk recording medium, the servo burst regions each being divided into at least two sub-regions in the traveling direction of a head, one sub-region having the same width as that of a track, and the other sub-region having a smaller width than that of the track.
It is preferable that the width of one sub-region is made smaller than that of a reading element.